/tmp/bitcoin/src/semaphore_grant.h

Source
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_SEMAPHORE_GRANT_H
#define BITCOIN_SEMAPHORE_GRANT_H

#include <semaphore>

/** RAII-style semaphore lock */
template <std::ptrdiff_t LeastMaxValue = std::counting_semaphore<>::max()>
class CountingSemaphoreGrant
{
private:
    std::counting_semaphore<LeastMaxValue>* sem;
    bool fHaveGrant;

public:
    void Acquire() noexcept
    {
        if (fHaveGrant) {
            return;
        }
        sem->acquire();
        fHaveGrant = true;
    }

    void Release() noexcept
    {
        if (!fHaveGrant) {
            return;
        }
        sem->release();
        fHaveGrant = false;
    }

    bool TryAcquire() noexcept
    {
        if (!fHaveGrant && sem->try_acquire()) {
            fHaveGrant = true;
        }
        return fHaveGrant;
    }

    // Disallow copy.
    CountingSemaphoreGrant(const CountingSemaphoreGrant&) = delete;
    CountingSemaphoreGrant& operator=(const CountingSemaphoreGrant&) = delete;

    // Allow move.
    CountingSemaphoreGrant(CountingSemaphoreGrant&& other) noexcept
    {
        sem = other.sem;
        fHaveGrant = other.fHaveGrant;
        other.fHaveGrant = false;
        other.sem = nullptr;
    }

    CountingSemaphoreGrant& operator=(CountingSemaphoreGrant&& other) noexcept
    {
        Release();
        sem = other.sem;
        fHaveGrant = other.fHaveGrant;
        other.fHaveGrant = false;
        other.sem = nullptr;
        return *this;
    }

    CountingSemaphoreGrant() noexcept : sem(nullptr), fHaveGrant(false) {}

    explicit CountingSemaphoreGrant(std::counting_semaphore<LeastMaxValue>& sema, bool fTry = false) noexcept : sem(&sema), fHaveGrant(false)
    {
        if (fTry) {
            TryAcquire();
        } else {
            Acquire();
        }
    }

    ~CountingSemaphoreGrant()
    {
        Release();
    }

    explicit operator bool() const noexcept
    {
        return fHaveGrant;
    }
};

using BinarySemaphoreGrant = CountingSemaphoreGrant<1>;

#endif // BITCOIN_SEMAPHORE_GRANT_H

Line	Count	Source
1		// Copyright (c) 2009-2010 Satoshi Nakamoto
2		// Copyright (c) 2009-present The Bitcoin Core developers
3		// Distributed under the MIT software license, see the accompanying
4		// file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6		#ifndef BITCOIN_SEMAPHORE_GRANT_H
7		#define BITCOIN_SEMAPHORE_GRANT_H
8
9		#include <semaphore>
10
11		/** RAII-style semaphore lock */
12		template <std::ptrdiff_t LeastMaxValue = std::counting_semaphore<>::max()>
13		class CountingSemaphoreGrant
14		{
15		private:
16		std::counting_semaphore<LeastMaxValue>* sem;
17		bool fHaveGrant;
18
19		public:
20		void Acquire() noexcept
21	6.02k	{
22	6.02k	if (fHaveGrant) {
23	0	return;
24	0	}
25	6.02k	sem->acquire();
26	6.02k	fHaveGrant = true;
27	6.02k	}
28
29		void Release() noexcept
30	10.0k	{
31	10.0k	if (!fHaveGrant) {
32	3.85k	return;
33	3.85k	}
34	6.19k	sem->release();
35	6.19k	fHaveGrant = false;
36	6.19k	}
37
38		bool TryAcquire() noexcept
39	170	{
40	170	if (!fHaveGrant && sem->try_acquire()) {
41	170	fHaveGrant = true;
42	170	}
43	170	return fHaveGrant;
44	170	}
45
46		// Disallow copy.
47		CountingSemaphoreGrant(const CountingSemaphoreGrant&) = delete;
48		CountingSemaphoreGrant& operator=(const CountingSemaphoreGrant&) = delete;
49
50		// Allow move.
51		CountingSemaphoreGrant(CountingSemaphoreGrant&& other) noexcept
52	12	{
53	12	sem = other.sem;
54	12	fHaveGrant = other.fHaveGrant;
55	12	other.fHaveGrant = false;
56	12	other.sem = nullptr;
57	12	}
58
59		CountingSemaphoreGrant& operator=(CountingSemaphoreGrant&& other) noexcept
60	643	{
61	643	Release();
62	643	sem = other.sem;
63	643	fHaveGrant = other.fHaveGrant;
64	643	other.fHaveGrant = false;
65	643	other.sem = nullptr;
66	643	return *this;
67	643	}
68
69	2.23k	CountingSemaphoreGrant() noexcept : sem(nullptr), fHaveGrant(false) {}
70
71	6.19k	explicit CountingSemaphoreGrant(std::counting_semaphore<LeastMaxValue>& sema, bool fTry = false) noexcept : sem(&sema), fHaveGrant(false)
72	6.19k	{
73	6.19k	if (fTry) {
74	170	TryAcquire();
75	6.02k	} else {
76	6.02k	Acquire();
77	6.02k	}
78	6.19k	}
79
80		~CountingSemaphoreGrant()
81	8.44k	{
82	8.44k	Release();
83	8.44k	}
84
85		explicit operator bool() const noexcept
86	172	{
87	172	return fHaveGrant;
88	172	}
89		};
90
91		using BinarySemaphoreGrant = CountingSemaphoreGrant<1>;
92
93		#endif // BITCOIN_SEMAPHORE_GRANT_H

Coverage Report

Created: 2026-09-21 19:49